Routine antenatal anti-D prophylaxis (RAADP) is recommended as a treatment option for all pregnant women who are rhesus D (RhD) negative and who are not known to be sensitised to the RhD antigen. A mother who is RhD negative can carry a baby who is RhD positive if her husband is positive. During pregnancy small amounts of fetal positive blood can enter the maternal circulation leading to the mother forming antibodies against the baby’s positive red blood cells. This is called sensitisation. Once sensitisation has occurred it is irreversible.
The anti-D antibodies produced by the mother can cross the placenta and affect the baby and future pregnancies that happen to be Rh positive, causing severe anaemia heart failure and even death. It also causes prolonged jaundice after birth in moderately affected babies. This when excessive deposits in the brain causing permanent damage.
To prevent all of the above, mothers who are Rh negative are given anti D at the times when the possibility is highest of fetal cells entering the mother’s blood. This is during the third trimester.
The recommendation is to give it at 28 and 34 weeks. If after the delivery the baby was negative, the mother gets no more. If the child is positive, the mother is given another dose post-delivery.
In cases such as those below, the mother also needs anti D as there is a chance of fetal cells entering the mother’s bloodstream. This has to be administered as soon as possible after the potentially sensitising event but always within 72 hours.
- Procedures such as amniocentesis;
- A late miscarriage;
- Ectopic pregnancy;
- Surgical treatment of miscarriage;
- Or severe trauma.
Early complete miscarriages before 12 weeks with no intervention do not require anti D.
Anti-D Ig should be given to all non-sensitised RhD-negative women who have a spontaneous threatened, complete or incomplete miscarriage at or after 12+0 weeks of gestation.
In women in whom bleeding continues intermittently after 12+0 weeks of gestation, anti-D Ig should be given at 6-weekly intervals.